Ferromagnetic Film, Magneto-Resistance Element And Magnetic Random Access Memory

Abstract

A ferromagnetic film according to the present invention includes ferromagnetic element and nonmagnetic element and has a first portion and a second portion. Concentration of the nonmagnetic element in the first portion is lower than an average concentration of the nonmagnetic element in the ferromagnetic film. On the other hand, concentration of the nonmagnetic element in the second portion is higher than the average concentration of the nonmagnetic element in the ferromagnetic film. The nonmagnetic element includes at least one element selected from the group consisting of Zr, Ti, Nb, Ta, Hf, Mo and W. The ferromagnetic film is applied to a magnetic free layer of a magneto-resistance element in an MRAM.

1 . A ferromagnetic film that includes ferromagnetic element and nonmagnetic element, comprising: 
 a first portion in which concentration of said nonmagnetic element is lower than an average concentration of said nonmagnetic element in said ferromagnetic film; and    a second portion in which concentration of said nonmagnetic element is higher than said average concentration,    wherein said nonmagnetic element includes at least one element selected from the group consisting of Zr, Ti, Nb, Ta, Hf, Mo and W.    
     
     
         2 . The ferromagnetic film according to  claim 1 , 
 wherein said ferromagnetic element includes at least one element selected from the group consisting of Fe, Co and Ni.    
     
     
         3 . The ferromagnetic film according to  claim 1 , 
 wherein said ferromagnetic film is crystalline and said second portion exists at a grain boundary.    
     
     
         4 . The ferromagnetic film according to  claim 3 , 
 wherein said first portion is formed to have a columnar structure.    
     
     
         5 . A ferromagnetic film comprising: 
 a ferromagnetic portion and a non-ferromagnetic portion that are phase separated,    wherein said non-ferromagnetic portion includes at least one element selected from the group consisting of Zr, Ti, Nb, Ta, Hf, Mo and W which are nonmagnetic elements.    
     
     
         6 . The ferromagnetic film according to  claim 5 , 
 wherein principal constituent of said ferromagnetic portion includes at least one element selected from the group consisting of Fe, Co and Ni which are ferromagnetic elements.    
     
     
         7 . The ferromagnetic film according to  claim 5 , 
 wherein said ferromagnetic portion is crystalline and said non-ferromagnetic portion exists at a grain boundary of said ferromagnetic portion.    
     
     
         8 . The ferromagnetic film according to  claim 7 , 
 wherein said ferromagnetic portion is formed to have a columnar structure.    
     
     
         9 . The ferromagnetic film according to  claim 1 , having a thicking of 1 to 20 nm.  
     
     
         10 . The ferromagnetic film according to  claim 1 , 
 wherein an atomic percent of an average concentration of said nonmagnetic element in said ferromagnetic film is lower than 30%.    
     
     
         11 . The ferromagnetic film according to  claim 1 , 
 wherein an atomic percent of an average concentration of said nonmagnetic element in said ferromagnetic film is higher than 5%.    
     
     
         12 . The ferromagnetic film according to  claim 1 , 
 wherein a roughness average of a surface is equal to or less than 0.3 nm.    
     
     
         13 . A ferromagnetic film including: 
 at least one first element selected from the group consisting of Fe, Co and Ni; and    at least one second element selected from the group consisting of Zr, Ti, Nb, Ta, Hf, Mo and W,    wherein a lattice constant is smaller than a lattice constant of an alloy in which said first element and said second element are distributed homogeneously.    
     
     
         14 . The ferromagnetic film according to  claim 13 , 
 wherein said lattice constant is a value obtained from a peak position of an X-ray diffraction measurement of an electron diffraction pattern.    
     
     
         15 . (canceled)  
     
     
         16 . A magneto-resistance element comprising: 
 a magnetic free layer;    a magnetic pinned layer; and    a nonmagnetic layer sandwiched between said magnetic free layer and said magnetic pinned layer,    wherein said magnetic free layer has a ferromagnetic film including ferromagnetic element and nonmagnetic element,    wherein said ferromagnetic film includes:    a first portion in which concentration of said nonmagnetic element is lower than an average concentration of said nonmagnetic element in said ferromagnetic film; and    a second portion in which concentration of said nonmagnetic element is higher than said average concentration.    
     
     
         17 . The magneto-resistance element according to  claim 16 , 
 wherein said ferromagnetic element is at least one element selected from the group consisting of Fe, Co and Ni, and    said nonmagnetic element is at least one element selected from the group consisting of Zr, Ti, Nb, Ta, Hf, Mo and W.    
     
     
         18 . A magneto-resistance element comprising: 
 a magnetic free layer;    a magnetic pinned layer; and    a nonmagnetic layer sandwiched between said magnetic free layer and said magnetic pinned layer,    wherein said magnetic free layer includes a ferromagnetic portion and a non-ferromagnetic portion that are phase separated.    
     
     
         19 . The magneto-resistance element according to  claim 18 , 
 wherein principal constituent of said ferromagnetic portion includes at least one element selected from the group consisting of Fe, Co and Ni, and    said non-ferromagnetic portion includes at least one element selected from the group consisting of Zr, Ti, Nb, Ta, Hf, Mo and W.    
     
     
         20 . The magneto-resistance element according to  claim 16 , 
 wherein said nonmagnetic layer is a tunnel insulating film.    
     
     
         21 - 25 . (canceled)